PHOENIX Lefthander David Holmberg is polite and unassuming, neither of which carries over when he takes the mound. The Diamondbacks appreciate both manifestations of his personality.

"His personality is such that attention is so unimportant to him," farm director Mike Bell said. "It doesn't interest him. But don't be fooled. He competes as well as anybody we have."

Obtained from the White Sox with righthander Daniel Hudson for righthander Edwin Jackson at the 2010 trade deadline, Holmberg features a fastball that sits in the 89-93 mph range and an array of offspeed pitches—curveball, slider, changeup—that he can throw for strikes. He has averaged almost nine strikeouts and 2.5 walks per game in his minor league career, and Bell compared him at this stage of his development to hard-throwing lefties Mark Buehrle and Joe Saunders.

Holmberg, 21, went 6-3, 2.99 with 86 sstrikeouts and 14 walks in 78 innings at high Class A Visalia before earning a promotion to Mobile, where he went 4-4, 3.86 in his first 12 starts with 53 strikeouts and 18 walks in 77 innings. This is the second straight year he has been bumped up a league at midseason.

"Steady Eddie, man. We got him at 18, and he was like that then," Bell said. "He'll be a big league starter at some point. He just has to keep logging innings."

A big man at 6-foot-3 and 223 pounds, Holmberg has gotten bigger in his back, shoulders and legs. "He's putting the weight in the right spots," Bell said.
SNAKE BITES

• Triple-A Reno lefthander Tyler Skaggs had given up one or fewer runs in seven starts dating back to July 6. Skaggs had given up four runs over 41 innings during that stretch, and was 4-1, 1.70 in eight starts with the Rawhide.

• Rookie-level Missoula catcher Michael Perez, a fifth-round pick out of Puerto Rico in 2011, had two home runs and five RBIs against Helena on Aug. 5, capping a streak in which he had 19 RBIs in nine games.